A Graphical Measure of Aggregate Flexibility for Energy-Constrained Distributed Resources
For grid operators managing distributed energy resources, this provides a simple graphical tool to assess fleet flexibility without complex computations.
The paper develops an analytical measure of aggregate flexibility for a fleet of energy storage units that cannot recharge, enabling immediate feasibility checks of demand traces and capability assessments like flexibility comparisons and ancillary service optimization.
We consider the problem of dispatching a fleet of heterogeneous energy storage units to provide grid support. Under the restriction that recharging is not possible during the time frame of interest, we develop an aggregate measure of fleet flexibility with an intuitive graphical interpretation. This analytical expression summarises the full set of demand traces that the fleet can satisfy, and can be used for immediate and straightforward determination of the feasibility of any service request. This representation therefore facilitates a wide range of capability assessments, such as flexibility comparisons between fleets or the determination of a fleet's ability to deliver ancillary services. Examples are shown of applications to fleet flexibility comparisons, signal feasibility assessment and the optimisation of ancillary service provision.